$7.)$ Two specimens of a same sand were prepared for direct shear tests. Specimen A wa: prepared to a dry density of $1\mathrm{.}56k\frac{N}{m^3}$ while the dry density of specimen B was $1\mathrm{.}78k\frac{N}{m^3}.$ Both specimens were sheared dry under the same normal stress of $100$kPa. Th dry density corresponding to the critical void ratio of the sand under $100$kPa is $1\mathrm{.}65k\frac{N}{m}$ Please sketch the variation of shear stress vs$.$ shear displacement and change of thicknes of the specimen vs$.$ shear displacement for specimen A and B$.$ Mark A and B clearly $(10\%)$